Nope, as you see the callid field is defined as simply a word followed
by an optional '@' with a trailing word. Just stick to the defined
values that make up a word and you're all set.
Since it seems you're looking for exact information then you should just
read rfc 3261 rather than asking for help multiple times within 10 mins:
8.1.1.4 Call-ID
The Call-ID header field acts as a unique identifier to group
together a series of messages. It MUST be the same for all requests
and responses sent by either UA in a dialog. It SHOULD be the same
in each registration from a UA.
In a new request created by a UAC outside of any dialog, the Call-ID
header field MUST be selected by the UAC as a globally unique
identifier over space and time unless overridden by method-specific
behavior. All SIP UAs must have a means to guarantee that the Call-
ID header fields they produce will not be inadvertently generated by
any other UA. Note that when requests are retried after certain
failure responses that solicit an amendment to a request (for
example, a challenge for authentication), these retried requests are
not considered new requests, and therefore do not need new Call-ID
header fields; see Section 8.1.3.5.
Use of cryptographically random identifiers (RFC 1750 [12]) in the
generation of Call-IDs is RECOMMENDED. Implementations MAY use the
form "localid@host". Call-IDs are case-sensitive and are simply
compared byte-by-byte.
Using cryptographically random identifiers provides some
protection against session hijacking and reduces the likelihood of
unintentional Call-ID collisions.
No provisioning or human interface is required for the selection of
the Call-ID header field value for a request.
For further information on the Call-ID header field, see Section
20.8.
Brandon
On 10/19/2011 04:23 AM, Srikanth satturi wrote:
> This is the rule i saw in forums,
>
> From 3261:
>
> callid = word [ "@" word ]
>
> word = 1*(alphanum / "-" / "." / "!" / "%" / "*" /
> "_" / "+" / "`" / "'" / "~" /
> "(" / ")" / "<" / ">" /
> ":" / "\" / DQUOTE /
> "/" / "[" / "]" / "?" /
> "{" / "}" )
>
> alphanum = ALPHA / DIGIT
>
> All of the mechanisms specified in this document are described in
> both prose and an augmented Backus-Naur Form (BNF) defined in RFC
> 2234 [10]. Section 6.1 of RFC 2234 defines a set of core rules that
> are used by this specification, and not repeated here. Implementers
> need to be familiar with the notation and content of RFC 2234 in
> order to understand this specification. Certain basic rules are in
> uppercase, such as SP, LWS, HTAB, CRLF, DIGIT, ALPHA, etc. Angle
> brackets are used within definitions to clarify the use of rule
> names.
>
> So I thought theremay be a explicit rule defined for call-id generation
>
>
> Srikanth
>
>
> On Wed, Oct 19, 2011 at 1:02 PM, Brandon W. Yuille <[email protected]
> <mailto:[email protected]>> wrote:
>
> Hi,
>
> The call id just needs to be a semi-unique identifier. The method
> for generating this is application specific, so there are no
> requirements for this value other than it should be unique in
> space and time. A common method I see in many sip applications is
> to generate a random value most likely also containing the current
> time concatenated with the ip address or host address of the
> application that is generating the call id.
>
> Example: "Call-ID: [email protected]
> <mailto:[email protected]>" or "Call-ID:
> [email protected] <mailto:[email protected]>"
>
> In that example imagine 0123456789abcdef is a base 16 sudo random
> number with a timestamp mixed in. You could use any base you'd
> like or come up with any form of more uniqueness.
>
> Hope this helps,
> Brandon
>
>
> Srikanth satturi wrote:
>> anyone please
>>
>> On Wed, Oct 19, 2011 at 12:40 PM, Srikanth satturi<
>> [email protected] <mailto:[email protected]>> wrote:
>>
>>
>>> Could please anyone help me out
>>>
>>>
>>> On Wed, Oct 19, 2011 at 12:23 PM, Srikanth satturi<
>>> [email protected] <mailto:[email protected]>> wrote:
>>>
>>>
>>>> Could anyone please give me rules for sip call id generation, in RFC
>>>> 3261
>>>> it is not clear, can i find specs anywhere. Please help me out
>>>>
>>>> --
>>>> Srikanth satturi
>>>>
>>>>
>>> --
>>> Srikanth satturi
>>>
>>>
>>
>
>
>
>
> --
> Srikanth satturi
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